Sure. Passive up-selling is fine. I hate aggressive up-selling. You have a very good point. I don't think there will be an easy way to figure out how much valu

Sure. Passive up-selling is fine. I hate aggressive up-selling. You have a very good point. I don't think there will be an easy way to figure out how much value each user will see in a product. Maybe try to up-sell through a mailing list? People interested in new offers could sign up.